This invention relates to a method of recognition of two-dimentional pattern data carried on a large sized drawing, document or the like, and to an apparatus for carrying out the method.
Conventionally, for scanning characters on a document by means of an optical character reader (referred to as an OCR hereinbelow), a sensor having photo-electric conversion elements arranged in a one-dimentional fashion is conventionally used, and the sensor is moved with respect to the document for scanning the two-dimentional image.
In the case of scanning a large sized document whose width cannot wholly be covered by a single sensor, a method is known wherein a plurality of sensors and corresponding lenses are used in such a way that individual portions of the document may be focused through the lenses into images on the respective sensors in a manner that one scanning line due to one sensor and another scanning line due to the other sensor are positioned to be connected to each other at a common connection point for forming one continuous scanning line.
In such a conventional method, however, even if two scanning lines due to two sensors could be precisely positioned for connection at a common connection point, there is a possibility of discrepancy at the connection point in the resultant pattern data obtained by the sensors because of characteristic differences between the sensors and/or between the lenses and/or because of quantization errors, thus resulting in an undesirable influence on recognition of such pattern data.
Further, in recognition of the pattern data obtained by a plurality of sensors, the whole pattern data must be stored in a temporary memory, which requires a very large storage capacity.
In an apparatus for recognition of a large sized drawing such as a draft, there are also similar problems as the above, and effective solutions of such problems have not yet been found.